Fabrication
This domain is about execution discipline: preparation, fit-up, preheat, consumable handling, sequencing and distortion control - and the records that prove them.
Core rules
- Cut edges to ISO 9013 classes; thermally cut or gouged surfaces must be cleaned before welding.
- Preheat is verified to ISO 13916 before the arc starts and monitored during welding; interpass temperature is measured on the weld face.
- Consumables: basic-coated electrodes are re-dried at 300–350 °C for 1–2 h as the manufacturer states, then held at 100–150 °C. Cellulosic electrodes must not be baked - they rely on their moisture for shielding gas.
- Distortion control: balanced or backstep sequences, presetting, symmetry, and the minimum number of passes consistent with the WPS.
- Tacks are part of the joint: made by a qualified welder, to a qualified WPS, fully fused into the root.
Worked example
An opened packet of basic electrodes has sat in a humid workshop. The correct response is not to judge by appearance. Re-dry at 300–350 °C for 1–2 h, hold at 100–150 °C in a heated quiver, and keep re-drying cycles within the manufacturer's limit; if the history is unknown, scrap them. The reasoning is hydrogen: coating moisture raises diffusible hydrogen and can push a borderline-CEV joint into cold cracking.
Traps
Baking cellulosic electrodes; using a quiver as a drying oven; accepting tacks from unqualified personnel; recording no preheat or interpass values; grinding that smears metal over lack of fusion instead of revealing it.